What does an open UST release mean?

It means a confirmed release from an underground tank has not yet received a no further action determination from the regulator. That can mean active cleanup, or long-term monitoring while contamination attenuates, or simply an unclosed file.

Should I worry about a gas station near my house?

A filling station alone is not a finding; a confirmed release near you, particularly an open one and particularly if you are down-gradient, is what deserves attention. The state's tank file gives the specifics, including whether groundwater was involved.

Who pays to clean up a leaking home heating oil tank?

Generally the property owner. Most states run petroleum cleanup funds with varying eligibility, and some homeowners' policies cover parts of it, but the default position is that it is the owner's cost. It is worth resolving before a sale rather than during one.

Guides

Underground storage tanks and what an open release means

There are over 740,000 tank facilities on EPA's national map and hundreds of thousands of recorded releases. Here is how to read one near you.

Updated 2026-09-03 - 6 min read

Why there are so many

Underground storage tanks hold petroleum and hazardous substances, most commonly at filling stations but also at fleet depots, farms, factories, schools and apartment buildings with oil heat. EPA's UST Finder maps more than 740,000 facilities nationally.

Tanks installed before the 1988 federal technical standards were often bare steel, and bare steel corrodes. That generation of tanks produced a very large number of releases, which is why the recorded release count is in the hundreds of thousands rather than the hundreds.

Open versus closed

A release record is 'open' until the regulator issues no further action, and 'closed' after. Umwelt reports both counts, and the open figure is the one that carries information.

Open does not necessarily mean active digging. It can mean monitoring wells are being sampled on a schedule while a plume attenuates naturally, which is a legitimate and common remedy that runs for years. It can also mean the file has simply not been closed out.

Closed does not necessarily mean clean. Closure standards vary by state and are frequently risk-based: contamination can be left in place if exposure pathways are judged incomplete for the land's current use. A change of use, such as building housing on a former commercial parcel, can reopen the question.

What it means for a specific property

Petroleum releases affect soil and groundwater and, where volatile fractions are present, can produce vapour intrusion into nearby buildings. The compounds of concern include benzene, toluene, ethylbenzene, xylenes and the fuel additive MTBE, which is unusually mobile in groundwater.

Direction matters more than distance, as with any groundwater question. A property down-gradient from an open release deserves closer reading than one further away but up-gradient.

If the property itself ever had a tank, that is a different and more serious question than a neighbouring release. Residential heating oil tanks are frequently exempt from federal rules, often undocumented, and a leaking one is the owner's problem: removal and remediation commonly runs from a few thousand dollars to well into five figures.

How to read the actual file

Tank and release records are administered by states, and the state file is where the detail lives. Search the state environmental agency's tank or LUST database by address or facility name; most publish this online, and the rest respond to public records requests.

Look for the release date, the contaminants confirmed, whether groundwater was affected, the remedy selected, whether monitoring is ongoing, and any land use restriction recorded on closure.

For a purchase where an open release is nearby or the property has tank history, this is the point where a consultant earns their fee: reading a state tank file correctly is a practised skill.

Common questions

What does an open UST release mean?: It means a confirmed release from an underground tank has not yet received a no further action determination from the regulator. That can mean active cleanup, or long-term monitoring while contamination attenuates, or simply an unclosed file.
Should I worry about a gas station near my house?: A filling station alone is not a finding; a confirmed release near you, particularly an open one and particularly if you are down-gradient, is what deserves attention. The state's tank file gives the specifics, including whether groundwater was involved.
Who pays to clean up a leaking home heating oil tank?: Generally the property owner. Most states run petroleum cleanup funds with varying eligibility, and some homeowners' policies cover parts of it, but the default position is that it is the owner's cost. It is worth resolving before a sale rather than during one.

Want to know what applies to one specific address? The free check reports what is on the federal record near it, and says plainly when nothing is. Check an address

Umwelt publishes public records and explains the standards that govern them. This is not legal, engineering, environmental consulting or medical advice, and it does not assess any specific property or person.